[paper] Vertical Graphene–hBCN Heterostructure TFETs

A comparative computational study of tunneling transistors

based on vertical graphene–hBCN heterostructures

Mahsa Ebrahimi¹, Ashkan Horri¹, Majid Sanaeepur², and Mohammad Bagher Tavakoli¹

J. Appl. Phys. 127, 084504 (2020); DOI: 10.1063/1.5130777

Published Online: 28 February 2020

¹Department of Electrical Engineering, Arak Branch, Islamic Azad University, Arak, Iran
²Department of Electrical Engineering, Faculty of Engineering, Arak, Iran

ABSTRACT In this paper, the electrical characteristics of tunneling transistors based on vertical graphene and a hexagonal boron-carbon-nitrogen (hBCN) heterostructure are studied and compared theoretically. We have considered three different types of hBCN, i.e., BC₂N, BC₂N₀, and BC₆N as a tunneling barrier. Our simulation is based on the nonequilibrium Green’s function formalism along with an atomistic tightbinding (TB) model. The TB parameters are obtained by fitting the band structure to first-principles results. By using this method, electrical characteristics of the device, such as the ION=IOFF ratio, subthreshold swing, and intrinsic gate-delay time, are investigated. For a fair comparison, the effects of geometrical variations and number of tunneling barrier layers on the electrical parameters of the device are simulated and investigated. We show that, by an appropriate design, the device can be used for low-power or high-performance applications. The device allows current modulation exceeding 106 at room temperature for a 0.6 V bias voltage.

FIG. DFT Band structure for (a) graphene - hBC₂N₀ - graphene (b) graphene - hBC₂N - graphene and (c) graphene - hBC₆N - graphene supercell. BC and BV represent barrier height in the conduction band and valence band, respectively, all simulated with QUANTUM ESPRESSO: A modular and opensource software for quantum simulations of materials